In one dimension, two waves with the same frequency, wavelength and amplitude traveling in opposite directions will interfere and produce a standing wave or stationary wave. For example: a wave traveling to the right along a taut string and hitting the end will reflect back in the other direction along the string, and the two waves will superpose to produce a standing wave. The reflective wave has to have the same amplitude and frequency as the incoming wave.
If the string is held at both ends, forcing zero movement at the ends, the ends become zeroes or nodes of the wave. The length of the string then becomes a measure of which waves the string will entertain: the longest wavelength is called the fundamental. Half a wavelength of the fundamental fits on the string. Shorter wavelengths also can be supported as long as multiples of half a wavelength fit on the string. The frequencies of these waves all are multiples of the fundamental, and are called harmonics or overtones. For example, a guitar player can select an overtone by putting a finger on a string to force a node at the proper position between the ends of the string, suppressing all harmonics that do not share this node.
What are harmonics?
Guitar Harmonics:
http://www.guitarlessonworld.com/lessons/harmonics.htm
Harmonics are played every time you pluck a note. Most of the time, however, you do not hear them. What you hear is the fundamental (sometimes called the first harmonic). The fundamental is the loudest sound produced, but it is accompanied by several harmonics. "Playing harmonics" on guitar is actually playing "artificial harmonics." Basically, it is a way of eliminating the fundamental and the other overtones. It produces a nice effect that many guitarists like to use. There are several ways to play these. Read more at: http://www.guitarlessonworld.com/lessons/harmonics.htm
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Digging Deeper
What is a standing wave?
Mathematical description
In one dimension, two waves with the same frequency, wavelength and amplitude traveling in opposite directions will interfere and produce a standing wave or stationary wave. For example: a wave traveling to the right along a taut string and hitting the end will reflect back in the other direction along the string, and the two waves will superpose to produce a standing wave. The reflective wave has to have the same amplitude and frequency as the incoming wave.If the string is held at both ends, forcing zero movement at the ends, the ends become zeroes or nodes of the wave. The length of the string then becomes a measure of which waves the string will entertain: the longest wavelength is called the fundamental. Half a wavelength of the fundamental fits on the string. Shorter wavelengths also can be supported as long as multiples of half a wavelength fit on the string. The frequencies of these waves all are multiples of the fundamental, and are called harmonics or overtones. For example, a guitar player can select an overtone by putting a finger on a string to force a node at the proper position between the ends of the string, suppressing all harmonics that do not share this node.
What are harmonics?
Guitar Harmonics:
http://www.guitarlessonworld.com/lessons/harmonics.htmHarmonics are played every time you pluck a note. Most of the time, however, you do not hear them. What you hear is the fundamental (sometimes called the first harmonic). The fundamental is the loudest sound produced, but it is accompanied by several harmonics. "Playing harmonics" on guitar is actually playing "artificial harmonics." Basically, it is a way of eliminating the fundamental and the other overtones. It produces a nice effect that many guitarists like to use. There are several ways to play these. Read more at: http://www.guitarlessonworld.com/lessons/harmonics.htm
How Do Shock Absorbers Work?
YouTube: Hydraulic Shock Absorbers
http://youtu.be/W4ZZYqRVzLc?t=1m